The present invention relates to an assisted braking device comprising a master piston mounted for sliding in a master cylinder, a jack having piston connected to the master piston by interconnection means, control means comprising a pedal, a source of assisting hydraulic pressure, a distributor adapted to feed the jack with assisting hydraulic pressure from the said source, and lever means adapted to operate the distributor in response to the actuation of the control means. Safety means which may be provided are brought into action in the event of the failure of the assisting hydraulic pressure, in order to enable the master piston to be displaced through the force applied directly by the control means.
In arrangements of this kind the lever means acting on the distributor are generally interposed between on the one hand the control means and on the other hand the jack piston. An arrangement of this kind makes it necessary to take special precautions in respect of sealing and gives rise to considerable friction. Considerable space is required. In addition manual operation in the event of failure of the assistance must overcome obstructing resistance, such as that resulting from the movement of the jack piston, which has become ineffective.
The main object of the present invention is the provision of an assisting braking device which is free from these various disadvantages, whose dimensions are small, and whose construction is simple and strong.